GLENAIR
Source: “The Effect of Frequency on The Dielectric Breakdown of Insulation Materials in HV Cable Systems.” 8
produce fundamental frequencies from 1 kHz to 4 kHz, using pulse-width modulated (PWM) switching frequencies up to 30 kHz . Due to several physical phenomena, including dielectric heating and ion accumulation, source frequency affects the dielectric strength of the insulation. Simply put, high frequency loads put additional stress on the insulation, leading to lower breakdown voltages. While most materials degrade with increased frequency, the sensitivity and degree of degradation vary between materials. Let’s take a look at the impact of higher frequencies on XLPE (a common insulating material in high-voltage cables) Most airborne interconnect test regimens do not include electrical tests using frequencies other than 60 Hz. For example, interconnect manufacturers perform DWV at 60 Hz in accordance with EIA-364- 20. In the case of distributed electric propulsion systems, however, Glenair considers it far more XLPE Breakdown Voltage at Various Source Frequencies Source Frequency Breakdown Strength (kV RMS /mm) Relative Change (vs 50 Hz) DC 438.4 ↑ 406.06% 50 Hz 86.63 - 300 Hz 74.95 ↓ 13.49% 500 Hz 73.02 ↓ 15.71% 1000 Hz 64.48 ↓ 25.57% 1500 Hz 57.36 ↓ 33.79% 2000 Hz 56.87 ↓ 34.35% 2500 Hz 51.96 ↓ 40.02%
Jiayang Wu, Huifei Jin, Armando Rodrigo Mor, Johan Smit; Delft University of Technology; 2017
interconnects, such as PowerLoad, are well-suited to support higher frequency generators, variable frequency drives, and other such equipment. In fact, for AEA applications operating at substantially higher frequencies, ignoring frequency derating could have dire consequences on performance and reliability. Similarly, using DC-rated products in AC applications is inadvisable given the need to optimize passenger safety. Operational Stress Factors In application, there are numerous operational factors that may affect long-term reliability of the electrical wire interconnect system including: • Increased temperature = decreased insulation effectiveness resulting in thermal aging and reduced dielectric strength. • Increased humidity = Increased leakage current, surface conductivity, and reduced dielectric and creepage (tracking) strength. • Increased mechanical stress = contact fretting, material embrittlement, and reduced dielectric strength. • Chemical exposure = surface corrosion, material breakdown, insulation aging, and reduced dielectric strength. • Increased voltage = increased insulation failure, electrochemical erosion and intrinsic breakdown. • Increased source frequency = increased dielectric heating, leakage current, and reduced dielectric strength. • Increased partial discharge = increased carbonization/ resistance, chemical degradation, and eroded insulation integrity
prudent to broaden the range of high- frequency testing to ensure our native airborne
While it is certainly possible that wire interconnect technologies qualified for use in automotive or
QwikConnect • July 2021
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